Friday, June 15, 2012

Another real-time rendering test with Brigade, set in the Urban Sprawl scene.

- 800x480 resolution

- 5 spp

- 2x GTX 580

- because there is very little noise, blurring (frame averaging) is turned off

UPDATE: A reader of this blog sent me a highly detailed mesh of a procedural mountain landscape (500k traingles), created with World Machine, which rendered extremely fast with Brigade. The image below took less than half a second to render (the lighting isn't great, but that's not the point of this test :)

UPDATE 2: some pictures of an upcoming demo (idea by Jeroen van Schijndel):

the refraction index of the window glass is probably too much, should be tweaked

Wednesday, June 13, 2012

There's a new trailer of "It's about time", a real-time path traced game running on Brigade, created by a team of eight IGAD students (International Game Architecture and Design) from the NHTV, the Netherlands:

Friday, June 8, 2012

Another test with the ray traced AO kernel in Brigade. This kernel holds the middle between distributed ray tracing [Cook] and full path tracing [Kajiya] and provides soft shadows, refraction, reflection (glossy and perfectly specular), depth of field and ambient occlusion with adjustable ray length, all raytraced in real-time and without screen space limitations or other hacks.

The best thing about this kernel is that the image converges so insanely fast that I've decided to tone down the frame averaging (blur) almost to zero. The little noise that still remains is mostly visible around shadow edges and on reflecting surfaces, but it's almost negligible compared to the amount of noise when using the path tracing kernel. Brigade is now extremely close to real-time noise-free rendering and this is still without any fancy noise filters.

If the current rate of development continues, you might expect to see the Brigade engine at E3 next year (disclaimer: kidding)

UPDATE: According to this article, Unreal Engine 4 uses a form of GPU based real-time ray tracing for global illumination called voxel cone tracing in a sparse voxel octree (SVOGI). The technique was pioneered by Cyril Crassin and was presented at Siggraph last year (sparse voxel octrees were all the hype in 2008 thanks to Jon Olick's Siggraph demo, which was researched further independently by Cyril Crassin and Samuli Laine). The future of real-time ray tracing on the GPU looks bright with one of the largest game companies starting to use it on a large scale :)

UPDATE 2: A reader of this blog just sent me a screenshot of an awesome stress test with the public Brigade version: a giant cube containing 729k (90x90x90) tiny cubes, a total of 8.75 million triangles, consuming ~ 2 GB of video memory. Thanks Nicholas!

"Progressive rendering is becoming a popular alternative to precomputation approaches for appearance design tasks. Images created by different progressive algorithms exhibit various kinds of visual artifacts at the early stages of computation. We present a user study that investigates the effects of these artifacts on user performance in appearance design tasks. Speciﬁcally, we ask both novice and expert subjects to perform lighting and material editing tasks with the following algorithms: random path tracing, quasi-random path tracing, progressive photon mapping, and virtual point light (VPL) rendering. Data collected from the experiments suggest thatpath tracing is strongly preferred to progressive photon mapping and VPL rendering by both experts and novices. There is no indication that quasi-random path tracing is systematically preferred to random path tracing or vice-versa; the same holds between progressive photon mapping and VPL rendering. Interestingly, we did not observe any signiﬁcant difference in user workﬂow for the different algorithms. As can be expected, experts are faster and more accurate than novices, but surprisingly both groups have similar subjective preferences and workﬂow."

During the first frame updates, progressive photon mapping exhibits low frequency noise in the form of ugly splotches, while VPL rendering suffers from banding artefacts. The noise produced by path tracing on the other hand is much more easy on the eyes showing that the human visual system is more forgiving for Monte Carlo noise.

About Me

Passionate about real-time path tracing and photoreal rendering with GPU ray tracing. I'm currently leading the scientific visualisation team at the EPFL Blue Brain Project in Geneva. Before that, co-founder and project lead at MI New Zealand, project lead at the University of Auckland NZ, technical project manager on OctaneRender (from pre-v1.0 beta to v2.0), instigator and driving force behind the Brigade real-time path tracing in games project leading the creative and technical R&D vision (Feb 2012 - Oct 2013), photoreal 3D graphics developer and consultant, medical imaging/neuroradiology researcher. My tutorial series on GPU accelerated path tracing (with source code) can be found on GitHub.
For questions, email me at sam.lapere@live.be